402 Dr. A. Smith Woodward—Fossil Fishes from Egypt. 
animal, it pays the penalty with its life. Most of the perforated 
blocks from the Fayim show the burrows passing completely through 
the masses. 
Pholades generally occur between tides from high to low water. 
Their burrows always hold sea-water, which is renewed with each 
tide. The Pholas is assisted by the grains of sand brought by each 
tide to bore downwards into the rock with its foot and so deepen its 
burrow. It is most improbable that Pholades could exist in a lake, 
however salt, as they require tidal action to carry on their existence. 
Mr. Beadnell writes, op. cit., p. 14: ‘‘The phenomenon of the 
extraordinary freshness of the Birket el Qurin has been commented 
on by Schweinfurth, who shows that the degree of concentration of 
salt in a lake whose volume has been continually reduced, and to 
which salt has constantly been added, should be many times greater 
than the actual existing amount.’’ An analysis’ of the water at the 
west end of the lake (where the concentration is greatest, owing to 
the distance from the feeder canals) showed that the total salts 
amounted to only 1°34 per cent., of which 0°92 per cent. was sodium 
chloride. 
VI.—On a Fossiz Sore anp A Fosstn Ext From tHE Eocene 
or Eeyrr. 
By Artuur SmitH Woopwarp, LL.D., F.R.S., of the British Museum 
(Natural History). 
(PLATE XXXIII.) 
WO well-preserved Teleostean fishes from the Eocene Limestone of 
Tura, between Heluan and Cairo,’ have been submitted to me 
by Dr. W. F. Hume, Director of the Geological Survey of Egypt. 
They apparently represent new species, but, like most fishes of Eocene 
age, they are remarkably modern in type, and one seems to be referable 
to an existing genus. With them were found remains of two species 
of Percoid fishes, which are scarcely sufficient for exact determination. 
1. Sonea EocEenIca, sp.nov. Pl. XXXIII, Figs. 1, 1a, 6. 
A small fish measuring 5:7 cm. in total length is a true Pleuronectid, 
and may be compared with the diminutive species of Solea, already 
known from the Lower Miocene of Wiirtemberg.? As shown by 
Pl. XXXIII, Fig. 1, the upper part of the anterior half of the 
specimen is broken away, but otherwise it is completely exhibited in 
direct left side view. 
The head with opercular apparatus occupies somewhat less than 
one-quarter of the total length to the base of the caudal fin. The 
maximum depth of the trunk must have equalled slightly less than 
half of this total length. Some of the head-bones are distinct and 
1 A Preliminary Investigation of the Soil and Water of the Fayim Province, 
by A. Lucas, Survey Department, Cairo, 1902. 
2 W. F. Hume, ‘‘ The Building Stones of Cairo Neighbourhood and Upper 
Keypt”’: Geol. Surv. Egypt, 1910, p. 44. 
' 3 Solea kirchbergana, H. von Meyer: Paleontographica, 1851, vol. ii, p. 102, 
pl. xvii, figs. 2, 3; also loc. cit., 1856, vol. vi, p. 25, pl. 1, fig. 3. 
